1. Field of the Invention
This invention relates, generally, to machinery. More particularly, it relates to mechanical grippers that engage flexible pouches.
2. Description of the Prior Art
Flexible pouches are in widespread use for holding a wide variety of products. Typically, a form, fill and seal machine includes multiple mechanical pouch gripper assemblies of metallic construction. One assembly includes a pair of grippers disposed in lateral relation to one another at opposite ends of the pouch. Various means are used to open a pouch so that product may be charged into it and for closing the pouch after the product has been charged into it.
The mechanical grippers of the prior art may drop the pouch if a heavy product is dropped into it because the gripping means is typically spring-loaded. The shock of impact can be sufficient to overcome the spring-loaded grip. If a heavy product is gradually charged into a pouch, the spring-loaded grip can be lost in a more gradual way but the result is the same.
This problem has been countered by increasing the strength of the springs that provide the power behind the metallic gripping surfaces of the prior art machines, but that creates the problem of forming depressions in the pouch where the gripper engages the pouch, due to the strength of the pinch required to prevent pouch dropping. These depressions mar the pouches, making them unsightly and the subject of customer complaints.
Prior art machines also employ an arcuate means for opening and closing pouches that causes the pouches to sometimes collapse upon themselves into an “S” shape. When such condition occurs, human operator intervention is required, thus defeating the purpose of the machine.
There is a need for a better pouch-holding gripper mechanism.
More particularly, there is a need for a non-metallic gripping means that does not mar the pouch.
There is also a need for a gripping means that does not reply upon springs to provide gripping power.
Perhaps the greatest need is for a gripper apparatus that increases its gripping strength in response to increased loads.
Still another need exists for a pouch opening and closing means that does not deform pouches into an “S” shape so that the need for human intervention during machine operation is reduced.
However, in view of the art considered as a whole at the time the present invention was made, it was not obvious to those of ordinary skill in the art how the needs could be met.